The invention relates to a short arc discharge lamp having a body.
One type of a short arc discharge lamp (hereinafter simply referred to as a “discharge lamp”) is known in which a lamp body (hereinafter simply referred to as a “body” is formed of an opaque insulating member and only a portion where light is to be extracted is formed of a translucent member. For example, reference is made to Japanese Unexamined Patent Application Publication No. S61-267253.
FIG. 4 is a cross-sectional view for describing an example of a configuration of a discharge lamp. The discharge lamp is provided with a body 40 and a window member 50. The body 40 includes therein a reflection surface 40a curved in a concave shape, and the window member 50 covers a front opening 40b of the body 40. The reflection surface 40a of the body 40 defines discharge space S surrounded by the reflection surface 40a and in which a cathode 42 and an anode 43 are disposed to oppose each other.
The window member 50 is supported by a ring-shaped flange 55. The ring-shaped flange 55 has a U-shaped cross-section, and includes an inner ring section 55a, an outer ring section 55b, and a coupling section 55c. The inner ring section 55a is tubular in shape, the outer ring section 55b is tubular in shape and is larger in diameter than the inner ring section 55a, and the coupling section 55c connects the inner ring section 55a and the outer ring section 55b together.
The window member 50 is fitted into the ring-like flange 55 and thus supported by the ring-like flange 55 such that a circumferential side surface of the window member 50 is brought into contact with an inner circumferential surface of the inner ring section 55a of the ring-shaped flange 55 through an unillustrated bonding layer.
A window assembly 56 formed by the window member 50 and the ring-shaped flange 55 supporting the window member 50 is provided in the front of the body 40 through a ceramic spacer ring 46 and a metal ring 45. The metal ring 45 serves to supply power to the cathode 42. The window assembly 56, the ceramic spacer ring 46, and the metal ring 45 are fitted together with the body 40 into a cylindrical first metal tubular body 48, thereby fixing the window assembly 56 to the body 40.
In FIG. 4, a reference numeral 47 denotes a conductive supporting member for disposing the cathode 42 at a predetermined position, and a reference numeral 49 denotes a second metal tubular body for fixing the body 40 to a metal block 41.